JP2002195860A - Vortex flowmeter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vortex flowmeter realizing a reduction in assembling man-hours and realizing the expansion of the scope of application relative to the kinds of fluids. SOLUTION: This vortex flowmeter is equipped with a columnar vortex generator provided perpendicularly to a pipe line to be measured and a vortex detector having a piezoelectric element embedded therein and provided downstream of the vortex generator, and measures the rate of flow by detecting an alternating force exerted on the piezoelectric element by a Karman vortex generated by the vortex generator. The vortex detector is airtightly fixed by ultrasonic welding to a pipe body constituting the pipe line. Further, a circular projection is provided on a flange formed on the vortex detector and 'a crimp pattern' is formed on its surface to be connected to the pipe body, thereby enhancing weldability.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small-sized plastic vortex flowmeter for measuring the flow rate of a fluid flowing through a small-diameter pipe, and to reduce the number of assembling steps and expand the range of application to the type of fluid. It relates to a flow meter.

[0002]

2. Description of the Related Art FIG. 4 is a sectional view of a small plastic vortex flowmeter showing a conventional example. In FIG. 4, reference numeral 1 denotes a tube, and a tube 1a through which the measurement fluid 2 flows is formed.
A vortex generator 3 is formed in the pipe 1, and a vortex detector 7 in which a piezoelectric element 4 is accommodated inside a sheath 6 is disposed downstream of the vortex generator 3.

In general, the material of the tube 1 and the sheath 6 is, for example, PPS resin when the measuring fluid 2 is general industrial water, and for example, PFA resin when the measuring fluid is pure water or chemicals.

FIG. 5 is a cross-sectional view of a main part in a state where the vortex detector 7 is fixed to the tubular body 1. The vortex detector 7 is formed in a T-shaped cross section having a flange portion 7a, is inserted into the pipe line 1a through a through hole 8 formed in the pipe body 1, and is fixed to the pipe body 1 by screws 9. I have. The tube 1 and the vortex detector 7 are O
Sealed by a ring 10 to prevent the measuring fluid from leaking out of the tube 1;

Returning to FIG. 4, when the measurement fluid 2 flows through the pipe 1a, a Karman vortex is generated by the vortex generator 3, and the alternating force acting on the piezoelectric element 4 by the Karman vortex is changed by a signal processing circuit (PCB) 11. It is possible to detect and measure the flow rate of the measurement fluid 2.

[0006]

In such a conventional apparatus, since an O-ring is used as a sealing member, it is necessary to select a material for a fluid to be measured. That is, nitrile rubber is used for general purposes, fluorine rubber is used for high temperatures, and perfluoroelastomer is used for chemicals. However, when the fluid to be measured is ultrapure water or a high-purity chemical, the liquid in the gap between the O-rings is used. In some applications, the elution of ions from the stagnation or the O-ring itself becomes a problem, and the use of the O-ring is not desired.

FIGS. 6A and 6B show a conventional example in which the tube 1 and the vortex detector 7 are fixed by welding without using such an O-ring. In the figure, the pipe 1 and the vortex detector 7 are connected by welding in FIG. Next, as shown in FIG. 2B, the tube 1 is sandwiched and fixed between the upper cover 20 and the lower cover 21 to which the signal processing circuit (PCB) 11 is attached.

[0008] Since the welding connection hinders the use of a welding rod,
It is necessary to secure a space around the welding point. That is, if a space cannot be obtained, the surrounding resin pipe will melt during the welding operation. In addition, upper and lower covers are required to protect the signal processing circuit 11 and the like. In this case, the number of components is increased, the number of assembly steps is increased, and the cost is increased.

The present invention solves the above-mentioned problems. An object of the present invention is to provide a vortex flowmeter that reduces the number of assembling steps and expands the applicable range for the type of fluid.

[0010]

In order to achieve the above object, according to the present invention, in the first aspect, a columnar vortex generator provided orthogonally to a measurement pipe and a piezoelectric element are embedded. A vortex detector provided downstream of the vortex generator, wherein a Karman vortex generated by the vortex generator detects an alternating force acting on the piezoelectric element to measure a flow rate, wherein the vortex flowmeter The detector is air-tightly fixed to the pipe constituting the pipe by ultrasonic welding.

According to a second aspect of the present invention, in the thermal flow meter according to the first aspect, the vortex detector has a flange portion, and the flange portion and the tube are fixed by ultrasonic welding. Features. It is characterized by the following.

According to a third aspect of the present invention, in the thermal flow meter according to the second aspect, a ring-shaped convex portion is formed on a surface of a portion where the flange portion contacts the pipe.

According to a fourth aspect of the present invention, in the thermal flow meter according to the second aspect, a "grain pattern" is formed at a portion where the flange portion contacts the pipe.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 (a) to 1 (c) are explanatory views of a main part of an embodiment of the present invention. FIG. 1 (a) is a plan view and FIG. 1 (b) is a view (a). (A) is a sectional view taken along the line AA, and FIG. (C) is a sectional view taken along the line BB in FIG. In these figures,
4 differs from the conventional example shown in FIG. 4 in the structure of the tube 1 and the method of fixing the vortex detector 7 to the tube.

That is, in this embodiment, the tube 1 and the vortex detector 7 are fixed by ultrasonic welding. The tube 1 used in the present invention is a conventional lower cover 20 shown in FIG.
And the tube 1 are integrally formed, and the top cover 21 is attached to the integrally formed tube. 11 is a signal processing circuit (P
CB) Fixing member.

Reference numeral 24 denotes a flange holder having a hole 24a formed in the center. The flange retainer reinforces the welded portion when the measured fluid pressure is high, and is formed to have a convex cross section. The tip of the vortex detector 7 is inserted into the hole 24a, and the flange 7 is screwed by the screw 9. Press to the tube 1 side.

FIGS. 2A to 2C show the sheath shape of the vortex detector 7 used in the present invention. FIG. 2A is a plan view, and FIG. 2B is AA in FIG. Sectional view, Figure (c) is Figure (a)
5B is a sectional view taken along line B-B, and a portion indicated by e in FIG. In these figures, the portion indicated by a is a contact point for sealing, and is a projection formed in a circular shape near the center of the portion where the flange portion 7a contacts the tubular body 1.

These projections function as a means for concentrating energy during ultrasonic welding to promote welding. Incidentally, the projection shown by a is 90, for example, as shown in FIG.
The height was about 0.2 mm at an angle of °. Further, a “grain pattern” is formed in a portion where the flange portion 7 a on the side where the protrusion is formed contacts the tubular body 1.

The "grain pattern" is a wrinkle having a roughness of about several tens of mpp formed on the surface. The wrinkle pattern is formed on a mold in advance and formed at the same time when the vortex detector is formed. . The “grain pattern” is defined as follows. "Shibo" = "texture" = "wrinkle"

In the plastics technical terminology, leather, satin finish, wood grain, cloth grain, etc. to be applied as a design pattern on the surface of a molded product are called "grain" or "grain pattern". Generally, irregularities appearing on the surface of the fabric, depending on how the yarn of the fabric is twisted.
Or it is uneven like a wrinkle processed on leather or paper.

3 (a) to 3 (c) show the shape of a welding horn for ultrasonic welding used in the present invention. FIG. 3 (a) is a plan view, and FIG. 3 (b) is AA in FIG. 3 (a). FIG. 2C is a cross-sectional view of FIG. In these figures, a hole 30a is formed in the welding horn 30, and the tip of the vortex detector 7 is inserted into this hole to perform ultrasonic welding.

According to the above-described structure, the vortex detector 7 and the tube 1 are connected by ultrasonic welding, and furthermore, a projection or a "grain pattern" is formed on the contact surface, so that good welding is possible. Since ultrasonic welding is performed by inserting the tip of the vortex detector 7 into the hole formed in the welding horn, there is no need to secure a space around the welding location, and there is no fear that the surrounding resin pipe will melt.

The foregoing description of the present invention has been presented by way of illustration and example only and in certain preferred embodiments. It will be apparent to those skilled in the art that many changes and modifications can be made in the present invention without departing from its essentials. The scope of the present invention defined by the description in the claims section is intended to cover alterations and modifications within the scope.

[0024]

As described above in detail, according to the first aspect of the present invention, since the vortex detector is fixed to the pipe constituting the pipe by ultrasonic welding, the number of assembling steps can be reduced. The range of application for the type of fluid can be expanded.

According to the second aspect, since the flange portion is formed on the vortex detector and the flange portion and the pipe are fixed by ultrasonic welding, the entire circumference can be simultaneously welded using the welding horn.

In the third aspect, a ring-shaped projection is formed on the surface of the portion where the flange portion comes into contact with the pipe, so that the weldability is improved.

According to the fourth aspect of the present invention, since a "grain pattern" is formed at a portion where the flange portion comes into contact with the tube, the flange is formed with a hook, so that the weldability is improved by a synergistic effect with the above-mentioned projection.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a main configuration showing an example of an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a vortex detector used in the present invention.

FIG. 3 is a diagram showing an example of ultrasonic welding using a welding horn used in the present invention.

FIG. 4 is a main part configuration diagram showing a conventional example.

FIG. 5 is a cross-sectional view showing a conventional seal structure using an O-ring.

FIG. 6 is a sectional view showing an assembled state by a conventional welding structure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Tube 2 Measurement fluid 3 Vortex generator 4 Piezoelectric element 7 Vortex detector 7a Flange part 9 Screw 10 O-ring 11 Signal processing circuit (PCB) 21 Top cover 24 Flange holder 30 Ultrasonic welding horn

Claims (4)

[Claims] 1. A vortex generator having a columnar vortex generator provided orthogonally to a measurement pipe, and a vortex detector having a piezoelectric element embedded therein and provided downstream of the vortex generator. In a vortex flowmeter for measuring a flow rate by detecting an alternating force in which the generated Karman vortex acts on the piezoelectric element, the vortex detector is air-tightly fixed to a pipe constituting the pipe by ultrasonic welding. A vortex flowmeter. 2. The vortex flowmeter according to claim 1, wherein the vortex detector has a flange portion, and the flange portion and the tube are fixed by ultrasonic welding. 3. The vortex flowmeter according to claim 1, wherein a ring-shaped convex portion is formed on a surface of the portion where the flange portion contacts the pipe. 4. A vortex flowmeter according to claim 1, wherein a "grain pattern" is formed at a portion where said flange portion comes into contact with the tube.